Water may contain many different kinds of contaminants including, for example, particulates, harmful chemicals, and microbiological organisms, such as bacteria, parasites, protozoa and viruses. In a variety of circumstances, these contaminants must be removed before the water can be used. For example, in many medical applications and in the manufacture of certain electronic components, extremely pure water is required. As a more common example, harmful contaminants in water must be removed, reduced to a harmless level, or deactivated (which is sometimes referred to as “killing”), before the water is potable, i.e., fit to consume. Despite modern water purification means, the general population is at risk, and in particular infants and persons with compromised immune systems are at considerable risk.
In the U.S. and other developed countries, municipally treated water typically includes one or more of the following impurities: suspended solids, bacteria, parasites, viruses, organic matter, heavy metals, and chlorine. Breakdown and other problems with water treatment systems sometimes lead to incomplete removal of bacteria and viruses. In other countries, there are deadly consequences associated with exposure to contaminated water, as some of them have increasing population densities, increasingly scarce water resources, and no water treatment utilities. It is common for sources of drinking water to be in close proximity to human and animal waste, such that microbiological contamination is a major health concern. As a result of waterborne microbiological contamination, an estimated six million people die each year, half of which are children under 5 years of age.
Another source of contamination of drinking water supplies is chemical contaminants, such as chlorine, taste, odor, lead, arsenic, volatile organic compounds (VOC), trihalomethanes (THM), chromium, etc. As an example, trihalomethanes (THM), which are by-products that can occur when residual chlorine from water treatment processes reacts with organic materials in the water, are found in many water sources around the world. These materials can occur naturally, and can be unintentionally formed in water supplies when organic compounds, for example industrial waste, leaches into water bodies that are subsequently treated with chlorine. In the water treatment and filtration industries, THM represent a wide class of compounds, and are typically called “total trihalomethanes” (TTHM). TTHM can be carcinogenic and may cause more immediate health issues such as rashes and other skin irritations. Moreover, TTHM can, and often do, have a profoundly negative effect on the taste of drinking water. Thus, the removal of TTHM from water is highly desirable.
Methods and filters for removing TTHM and other organic compounds from water are known. But the methods and filters are different than, and often inconsistent with the removal of small particles such as bacteria and viruses. As such, consumers of water are often required to have two or more filters, or one multi stage filter, to meet all of their filtration requirements. Multi-stage filters and multiple filters often require more space, and more expense than a single filter.
Hence, there exists a need for single stage filters that can remove different contaminants that have variant properties. That is, a filter that can be produced from a unitary material, albeit a material that may be a mixture of different components, in a one step process, resulting in a single stage filter having multiple removal capacity. More specifically, there is a need for a single stage filter that can simultaneously remove small particles, such as viruses and bacteria, as well as organic compounds, such as TTHM. This and other benefits are provided by the present invention.